This invention is in the field of information and communications, and is more specifically directed to improved processes, circuits, devices, and systems for position sensing and other information and communication processing purposes, and processes of making them. Without limitation, the background is further described in connection with wireless communications processing.
Wireless communications, of many types, have gained increasing popularity in recent years. The mobile wireless (or “cellular”) telephone has become ubiquitous around the world. Mobile telephony has begun to communicate video and digital data, in addition to voice. Wireless modems, for communicating computer data over a wide area network, using mobile wireless telephone channels and techniques are also available.
Wireless data communications in wireless local area networks (WLAN), such as that operating according to the well-known IEEE 802.11 standard, has become especially popular in a wide range of installations, ranging from home networks to commercial establishments. Short-range wireless data communication according to the “Bluetooth” technology permits computer peripherals to communicate with a personal computer or workstation within the same room. Personal area networks and piconetworks can provide decentralized networking from and between furniture, appliances, clothing and other locations.
GPS (Global Positioning System) is an earth-satellite-based electronic system for enabling GPS receivers in ships, aircraft, land vehicles and land stations to determine their geographic and spatial position such as in latitude, longitude, and altitude. Discussion of GPS herein is without limitation to other analogous satellite-based electronic systems.
A GPS receiving unit that has been powered down or has been without satellite signal coverage for a period, needs an accurate initial clocktime (referred to the GPS satellite atomic clock). Accurate initial clocktime is needed in order to use, make or achieve the shortest possible time to first position fix and to achieve the best possible positioning accuracy. In other words, a satellite positioning receiver would desirably have an accurate time estimate of the current time when commencing reception, in order to minimize the time consumed in obtaining a position fix.
Under such powered-down or no-satellite coverage conditions, the time could be gotten from the network by special assisted data, if available, for time-of-day based on network transmissions but for which link delay may create inaccuracy in the time-of-day information passed to the positioning unit. Also, the positioning unit could be connected at some inconvenience and expense to a network that is synchronized to the atomic clock of the satellite system. It would be desirable to accurately, reliably, conveniently and economically maintain an accurate time estimate when a satellite positioning receiver (SPR) and its clock source are deliberately powered down periodically to save power and powered down during other intervals for various reasons.
It is also desirable to obtain and maintain an accurate time estimate when a satellite positioning receiver and its clock source are associated with a cellular or other communications network distinct from the satellite positioning network, and the cellular transceiver clock is either inaccurate or alternated between a less than fully-accurate operational clock source and a less than fully accurate sleep mode clock source. Moreover, it would be desirable to provide ways of providing accurate time estimation from the cellular network wherein the cellular transceiver is subject to handover or handoff between cellular base stations as the cellular transceiver is moved from one cellular network cell to another cell.
It is desirable to find ways of swiftly providing accurate time to a satellite positioning receiver (SPR such as GPS) connected to a cellular transceiver such as a cell phone handset, or connected to any other asynchronous communications network with a less accurate time base than GPS, when the SPR only receives satellite signals at certain intervals, such as for power savings, and the cellular transceiver is camped on an asynchronous network.
Digital signal processing (DSP) chips and/or other integrated circuit devices are essential to these systems and applications. Reducing the cost of manufacture and device and system power dissipation and increasing speed of operation without compromising performance are important goals in DSPs, other processors, integrated circuits generally and system-on-a-chip (SOC) and other system design. These goals are especially important in hand held/mobile applications where small size is so important, to control the cost and the power consumed while enhancing performance.
It is desirable to solve any or all of the above problems, as well as other problems by improvements described hereinbelow.